Cross-feed mechanism for grinding machines



Feb. 27, 1945. R. s. PYNE ET AL CROSS FEED MECHANISM FOR GRINDING MACHINES 3 Sheets-Sheet l Filed Jan. 23, 1943 mvemons Roar) \iPr/vz A/VD Feb. 27, 1 R. s. PYNE ET AL CROSS FEED MECHANISM FOR GRINDING MACHINES Filed Jan. 25, 1945 3 Sheets-Sheet 2 mm MA s 0 A mM EH R V 0 0 m M T M A @M W 5- R. s. PYNE ET AL ,58

' CROSS FEED MECHANISM FOR GRINDING MACHINES Filed Jan. 25, 1943 3 Sheets-Sheet I5 (1.4 real ATTOR Ys Patented Feb. 27, 1945 i MACHINES Roger S. Pyne,'Longmeadow,- and Edward. A. Allen, Westfield, Mass; assignors toVan Nor- Y man Company, a corporation of Massachusetts Application January 23, 194-3, Serial No..473,352

7 Claims. (01. vi zso) .This invention relates to cross feed mechanism for grinding machines and the like; and has for its object the provision of cross feeding mechanism which will give a slow continuous feeding motion'adjustable in rate by altering the speed ofthe. driving element, and which will give a rapid'return motion by a mere reversal of the driving element without changing its rate. A further object is to provide such a mechanism with means whereby the cross feed may be subjected to hand control atany time and in either.

direction merely by rotating a hand control, and in which the rotation of said control serves automatically to cut off the cross feed from its power drive whereby manual operation is rendered easier. A further object is .to provide a differential or epicyclic drive for a cross feed with means for locking the epicyclic train'when the .driving element is reversed. Afurther object is to provide a cross feeding mechanism power driven through a friction clutch and having a manual control; in which mechanism is provided to reduce the drag of the friction clutch whenthe manual control is operated. A further object is to, provide a compact cross feeding mechanism capable of being driven from a variable speed motor. Additional objects will appear from the following description and claims. r Referring to the drawings,

Fig. 1 is a front elevation of a portion of the bedof a grinding machine embodying our improved cross feeding mechanism;

Fig. .2 .is a top plan thereof with certain parts removed;

Fig. 3 is a detail section of parts appearing in Fig. 4 but-taken in a plane at right angles to the plane of the latter figure; .Fig. 4 is a section on line 4-. l of Fig. 1;

Fig. 5 is asection on line 55 of Fig. the parts in a neutral position; a

- Fig. 6 is a section on line 6-5 of Fig. 5 with the parts in feed position;

a Fig. 7 is a viewsimilar to Fig. 5.showing the parts in feed position; i

Fig. 8 is a similar view showing the parts in the position they occupy duringreversal;

4 with Fig. 9 is a view similar to Fig. 6 showing the parts .in the position they occupy during reversal; and

, Fig. 10 is an enlarged view corresponding to a portionof Fig. lbut with part of the casing broken away to disclose the internal construction: .In Fig.1 is shown a portion [0 ofthe frame of a grinding machine having a cross slide H carrying either the work or the tool. The grindmg machine may be-adapted for cylindricalbor'e; or surface grinding, and'the details of .construction need not be shown as they will-vary .a 1

known manner in accordance with the nature of the work which the machine isintended to do. As is customary, the slide is provided with a nut (not shown) into-which is threaded a feed screw l2. This screw is driven by the cross feedmech anism continuously in one direction" at a siow rateto cause-feeding movement of theislida-and at a relatively rapid rate in the opposite 'diriec; tion to cause a rapid return movement-of the slide.

' Power for actuating the cross feed is prefer--' ably secured from a reversible, variable-speed motor I3 which may be of any desired type. The shaft of this motor carries a worm M'meShing with a worm wheel l5 forming part of a cage rotating freely on a pair of ratchet-carriers 11,13.

Each of these'carriers I1, I8 is freely rotatable on a sleeve [9 which in turn is rotatable on a driving sleeve 20. Through the sleeve"20, and coupledto it by a pin and slot connection 2|, is a shaft 22 having at one end a pinion 23 meshing with a gear 24 on the feed screw' l2. Cage 16 has a pivot shaft 25-secured therein which carries, preferably on needle bearings 26, .a pair of connected gears 21, 28 meshing respectively with gears 29, on the ratchet-carriersv I'l l8.

Ratchet-carrier 18 has a gear-toothed ratchet 3l formed thereon which coacts with a pawl 32 pivotedxat 33 to the housing 34 of the cross feed mechanism and pressed towards and away from the ratchet by a friction spring band 35 encircling a groove in the case 16 and having offset portions engaging a pin 35' on the pawl with a slight lost motion. The pawl holds the carrier l8 against rotation in one direction but permits, it

to rotate freely in the other. As will'be pointed out below, rotation of the cage [6 in the direction of the arrow 36 (in which direction corresponding rotation of the carrier l8 will be. prevented by the pawl). produces rotation of the screwlZ in the samedirection at a feed rate; while rotation; of the cage [6 in the opposite direction, as shown in Fig. 9 by arrow 3'! (in which direction rota-,

tion of the carrier 18 will be permitted by the pawl), causes reverse rotation of screw .12 at-a relatively rapid rate. Ratchet-carrier l1 carries will be lifted by pin 4| so as to slip freely over the ratchet 38 (Fig. 7); but when the direction of the cage is reversed as in Fig. 8 the pawl will be pressed against the ratchet by pin 4| so as to drive the carrier I1 positively from the cage I6.

Carrier I! has fixed to it an annular disk 43 so as to form an. internal recess enclosing a pair of friction plates, 45. Plate 44 is formed on one end of sleeve 20, which as previously stated is pinned to the feed screw driving shaft 22. Plate. 45 is slidable on shaft 22, has a sliding pin driv- 22 of suflicient grip so thatforall'grinding'op erations the connection is for practical purposes rigid. It should be remembered that theamount of cross feeding movement per cycle is measured in thousandths of an inch or less, and that the power required for the feed is'relatively small. The friction clutch mechanism is, however, capable of being made to slip when manual operation is desired, and in accordance withone feature of the invention the frictional drag is automatically decreased by the act of operating the manual drive, as will be described in detail below. Before going into that matter, however, it may be clearer to consider the manner in which the mechanism already discussed will operate in both forward and reverse directions.

Let first the worm l4 be driven in the feeding the moto'rwill be driven at a relatively rapid rate, while for finish grinding the speed'of the motor can be reduced by the use of suitable resistances and control elements which are standard in the use of motors of that type. Control of motor speed may be manual, or may be underZ-the control of gauges, dogs, and the like as will be well.understood by those skilled in the art, andmay have any desired gradations between the first rough feed and the final slow finishing' speed. As long as the direction of rota tion of the worm l4 is-in the feeding direction, however, the cage 16 will be rotated in the sense of the arrow 42'of Fig. '7. The ratchet and pawl connection'38, 39 will be disconnected-by pin 4| in this direction of movement, so that the drive of; the friction clutch is solely through the differential gears. As the cage revolves, the pivot pinion 21 must move bodily around the axis of shaft 22 without rotation on its own axis, and this of course carries pinion 28 in the same manner. Gear 3|) will thus be rotated and the carrier l8 will turn in the direction of arrow 31 (Fig. 9), in which it is not impeded by the sta tionary pawl 32 since this pawl has been drawn out of contact with its ratchet as described.

During this reverse motion carrier I8 is without function, the drive of shaft 22 being directly from cage Hi to carrier 1' and thence to the shaft through the friction clutch. It will be seen that this direct drive will be the same in speed as that of cage 16, whereas the forward motion of the permit a relief of pressure between the pawl 32 shaft 2 5'is carried bodily with it, and the connected gears. 21, 28 will be rolled around on gears 29, 3 9 formed on the carriers l1, l8. Since "carrier I8 is {prevented from rotation in this direction by the pawl 32, which is tilted into engagementwith the gear-toothed ratchet 3| by the drag of cage IS on the friction spring band 35, the pinions 2'|, 28 will be caused to rotate on their pivot shaft 25 as pinion 28 rolls around the then stationary gear 30, and carrier ll will be rotated by the interengagement of pinion 21 with gear 29 at a relatively slow rate dependent upon the differences in the numbers of teeth in the two gear pairs. This will cause rotation of the friction clutch, and through it and the shaft 22 a rotation of the feed screw l2 at a slow rate.

If now the direction of rotation of. the worm M be reversed the cage l6 will be-rotated in the direction of arrow 49 in Fig. 8. Due to the action of the pin 4| on the pawl 39 the ratchet 3B, the cage l6, and carrier Il will move as a unit. Since thereis in this case no relative movement between-cage l6 and thege'ar 29 on carrier the and the adjacent gear tooth before the pawl is rocked, thereby. preventing the pawl from being jammed tightly before it can be rocked into an inactive position. The lost motion between pins 4|, 4| and pawl 39 is shown as larger in amount, this being necessary because of the multiplying effect of the differential gearing, member l6 moving faster in feed than the member l8. While the exact mechanism shown may be varied, it is generally necessary to have some means for locking ratchet 3| against motion in both directions, as the differential gearing will develop a tendency to drive the carrier l-B unless the latter is locked. The friction drag mechanism described has proved in practice capable of performing this action satisfactorily.

Shaft 22 passes through a ball bearing 50 axially slidable in the housing, and has keyed to it a cam member 5|. One end of the cam member abuts a collar 52 through which a thrust train is established through bearing 5|] to the central portion of friction plate 45. The forward end of the shaft 22 has fixed toit a sleeve 53, between which and the hub 54 of a hand wheel 55 is a thrust bearing 55. Hub portion 54 and cam member 5| have one or more opposed depressions 51 (Fig. 3) receiving between them balls58. The hand wheel normally has a slight free rotation relative to the shaft, although it revolves with it, but in proportion to its rotation a wedging action of the balls 58 on the walls of depressions 51 is developed which forces the friction plate 45 away from the plate 43 against the force of spring 41. At the same time the wedging action couples the shaft and the handle together. The combined result of these actions is that the mere act of rotating the hand wheel manually both couples it tightly to the shaft'22 and releases the friction clutch. In connection with the latter effect it should be noted that while'the cams 5! act only to shift the friction member 45 the carriers I1, I 8 have a limited sliding'movement in an axial direction, so that the clutch action is maintained not by pressure of friction member 44 on the carrier I! but rather by an expanding force created by the separation of the two friction plates by the spring 41. Sleeve 29 is held against axial movement by the right hand bearing 60, so that when'axial pressure is directed against friction plate 45 it will be moved nearer to plate 44, which is held against movement by being a part of sleeve 20. The surfaces of members I6 and 43 against which the friction members act are, however, permitted slight axial movement, so that the pressing together of the frictionplates will effectively relieve any pressure against the coacting surfaces.. The slight drag which may result from contact without pressure of members H and 34 will exert no retarding force on the manual operation of shaft 22 by means of the hand wheel.

A bushing 6| is mounted around the cam member and has a conical bearing connection 62 therewith, against which it is pushed by a spring 63. The bushing thus can be adjusted around the shaft 22 as may be desired merely by pushing it in and turning it to the desired location. The bushing carries an abutment 64, preferably in the form of an eccentric which may be rotated to bring it to an inner inactive position, and coacts with a lever 65 controlling a conventional limit switch 66. If the eccentric is in its outer position the rotation of the shaft will carry the eccentric into contact with the lever 65 and will open the limit switch at the desired time as determined by the rotative adjustment; of the bushing 6|. This mechanism is desirable in some cases where control of the motor I3 by a size gauge in contact with the work is not desired, the limit switch 66 serving to open the motor circuit, when the feed has progressed to a predetermined point.

What we claim is:

1. In a feed mechanism for machine tools, a reversible, variable speed driving element, transmission means between said element and said mechanism for driving the latter in feeding direction at a slow rate adjustable by alteration of the speed of the driving element, and means automatically operable to increase the'speed ratio of said transmission upon reversal of the driving element without change in the rate of the latter, to drive said mechanism in the reverse direction at a rapid rate, means for manually driving said mechanism in either direction and means to automatically disconnect said transmission means upon actuation of said manual driving means.

2. In a feed mechanism for machine tools, a

' reversible, variable speed driving element, transmission means between said element and said mechanism, said transmission means including a differential through which the mechanism is driven in feeding direction at a slow rate and means for automatically locking said differential when the driving element is reversed to drive said mechanism in the reverse direction at av rapid rate without change in the rate of the driving element, means for manually driving said mechanism in either direction. and means to automatically disconnect said transmission means upon actuation of said manual driving means.

3. In a feed mechanism for machine tools, a shaft, a reversible, variable speed driving element, transmission means between the driving element and the shaft for driving the latter at a slow rate adjustable by alteration of the speed of the driving element, means automatically operable to increase the speed ratio of transmission upon reversal of the driving element without change in the rate of the latter to drive said mechanism in the reverse direction at a rapid rate without change in the rate of the driving element, a clutch between the shaft and transmission means, manual means for rotating the shaft and cam including a differential through which the shaft is driven in feeding direction at a slow rate, means for automatically locking said differential when the driving element is reversed to drive the shaft in the reverse direction at a rapid rate without change in the rate of the driving element, a clutch between the shaft and transmission means, manual means for rotating the shaft and cam means actuated by said manual means for disengaging said clutch upon actuation of said manual means.

5. In a feed mechanism for machine tools, a

stationary frame, a shaft, a pair of gears rotatably mounted on said shaft, one of said gears being coupled to the shaft, a cage mounted for rotation about said gears, connected pinions with unequal numbers of teeth carried by said cage and meshing respectively with the gears, a oneway clutch between one of said gears and the cage, an oppositely directed one-way brake between the other of the gears and the stationary frame, and means for driving the cage in reverse directions. I

6. In a feed mechanism for machine tools, a stationary frame, a shaft, a pair of gears rotatably, mounted on said shaft, one of said gears being coupled to the shaft, a cage mounted for rotation about said gears, connected pinions with unequal numbers of teeth carried by said cage and meshing respectively with said gears, a one-way clutch between one of said gears and the cage, means including a friction device operable to hold the clutch in or out of engagement depending upon the direction of rotation of the cage, a one-way brake between the other of said gears and the stationary frame, and means including a second friction device operable to hold the brake in engagement when the cage is revolving in a direction to cause the clutch to be disengaged and out of engagement when the cage revolves in the opposite direction.

7. In a feed mechanism for machine tools, a

stationary frame, a shaft, a pair of gears rotatably mounted on said shaft, one of said gears being coupled to the shaft, a cage mounted for rotation about said gears, connected pinions with unequal numbers of teeth carried by said cage and meshing respectively with said gears, a one-way clutch between one of said gears and the cage, means including friction and lost motion devices operable to shift the clutch into or out of engagement a predetermined interval after the initiation of rotation of the cage in one direction or the other respectively, a one-way brake between the other of said gears and the stationary frame, and means including friction'and lost motion devices operable to shift the brake into engagement a predetermined interval after the in 'itiation of rotation of the cage in a direction to 

